<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script type="text/javascript" src="js/vue.js"></script>
</head>

<body>
    <div id="app">
        消息的内容是: <span>{{ message}} </span>
        <p v-if="flag1"></p>
    </div>
</body>
<script>

    new Vue({
        el: "#app",
        data: {
            message: "This is a test",
            flag1: true,
            flag2: false
        }
    })



</script>

</html>